Read this article on how to adjust the TV cable.
http://www.73-87.com/garage/tvcable.htm
You know you have it right when you are in 2nd stomp the throttle and the tranny easily kicks down to 1st. At wide open throttle the TV cable end should be fully pulled out. Hold the carb at wide open throttle then take some needle nose pliers and pull on the TV cable. If more pulls out keep adjusting until it stops.